Cellulitis, abscess and necrotising soft-tissue infection: Viva

Branch 1: Classifying the infection and the purulent decision

The candidate should recognise that this child has both a purulent and a non-purulent element: a fluctuant abscess in the mid-forearm surrounded by a rim of cellulitis. The first decision, following the 2014 Infectious Diseases Society of America framework, is to separate purulent from non-purulent infection, because the therapy differs. The abscess is treated primarily by incision and drainage, while the surrounding cellulitis is treated with antibiotics directed at streptococci and staphylococci. ^[1]

The candidate should confirm the child is cardiovascularly stable and not toxic, which places her in the non-necrotising category for now, but should state explicitly the features that would trigger concern for necrotising infection: severe pain out of proportion to the visible erythema, systemic toxicity, tense woody induration, haemorrhagic bullae, crepitus, or rapid spread. The absence of these features in this child supports a purulent abscess with surrounding cellulitis rather than a surgical emergency. ^[3]